[AFD] TightVNC 2.7.10 sporadically blocking the system when disconnecting from a local loopback connection

r72998:
This is no regression, the following stuff did not work at all before haters recent fixes, still... when we get further we also start seeing new issues (sorry...)

-install TightVNC 2.7.10 from rapps
-open servers configuration window and check "allow loopback connections"
-use the viewer to connect to "127.0.0.1"
It should start building up an endless-mirror-cascade (this is totally correct)

Now try to disconnect the viewer again.
Often this works correctly, but sporadically this will hang up the GUI thread so that you have to reset ros (taskmgr is not enough to kill then anymore)

The log spams

(../drivers/network/afd/afd/write.c:424)(AfdConnectedSocketWriteData) Connection aborted

to no end then...